The Lunar Arctic Region. 53 



whose Section III. we have now entered, represents some ele- 

 vated masses much more steep and lofty than any which could 

 be identified by B. and M., the landscape appearing to them, 

 though mountainous, yet much more open. On its E. side we 

 meet with a curious bay, named Le Monnier, forming one of the 

 darkest portions of the Mare Serenitatis, and bounded by a 

 semicircle of steep and lofty cliffs — the half, to all appearance, 

 of a great ring. Of the other half, B. and M. could find no 

 trace ; they did not consider an insulated hill, lying out " at 

 sea," though in the right direction, any portion of it, its height 

 (3100 feet) being far inferior to that of the cliffs, which rise in 

 two places to upwards of 8000 feet, and the faintly distinguish- 

 able ridges connected with it taking wrong directions. It 

 must be noted, however, that these are otherwise drawn by 

 Lohrmann, and that two of them, according to his figure, very 

 fairly complete the circle. Minutiae of this kind must be at- 

 tended to by those who desire to throw light upon the origin 

 of the lunar formations. Although we are unable to detect the 

 existence of any " degrading" influence upon the surface of 

 the Moon, or to comprehend how its masses once erupted — if 

 such were their mode of creation — could, in the absence of air 

 and water, suffer any change excepting what might result from 

 slipping or earthquakes (the reader will pardon the solecism), 

 yet it cannot be denied that in many places there are indica- 

 tions of subsequent alteration which it is more easy to perceive 

 than to explain. Sometimes we might probably incline to the 

 idea that the appearance was deceptive, and must be referred 

 to other causes ; but those again are sufficiently obscure. The 

 question is a curious and interesting one, but requires to be 

 approached with much caution ; we find from the example of 

 geologists that even a personal examination of the lunar strata 

 might not exempt us from considerable perplexity. We have 

 already met in the M. Grisium with instances which would fall 

 within its range (Intellectual Observer, April, 1864, pp. 

 204, 205) and shall have to notice many hereafter. Le Mon- 

 nier is easily recognized under all circumstances of illumination, 

 reminding us in this respect, as well as in its general character, 

 of its gigantic counterpart, the Sinus Iridum (K in our map) 

 to be described at a future time. 



A little N. of Le Monnier we come to Posidonius (10), a 

 ring-plain of considerable importance, about sixty-two miles in 

 diameter,* remarkable for the defined outline of its wall, which 

 is, however, of no especial height.f A long curved ridge 



* Lohrmann gives nearly seventy-four miles : Schroter, about sixty-nine. 



t An evident mistake, probably a misprint, in the text of B. and M., prevents 

 their measures from being available. Schroter gives about 3000 feet to three of 

 its peaks on the E. side, above the M. Serenitatis. 



